1. Field of the Invention
The present invention at hand involves a computerized method to predict the diastolic rest period in the cardiac cycle as well as a method to depict the coronary arteries by means of magnetic resonance imaging. The diastolic rest period is predicted in order to use it later for diagnostic imaging.
2. Description of the Prior Art
Angiographic examinations of the coronary arteries are made by using x-ray equipment to depict the coronary arteries in order to detect constrictions in the coronary arteries. By means of magnetic resonance imaging, it has recently also been possible to produce images of the course of the coronary arteries. However, these so-called MR angiographies of the coronary arteries, however, may require a measuring (data acquisition) period of up to 30 minutes.
To record MR images of the heart, the rest period of the heart at the end of the diastole is used in order to depict the coronary arteries of the heart. At the same time, the ECG signal of the examined patient is used to record the MR images in order to determine the position of the diastolic rest period of the examined patient so that the MR images can be recorded during this rest period. The period for recording MR images in the rest period of the heart in the diastole is between 50 and 200 ms. In this period, the image data for the MR angiography is acquired, whereby in this case segmented recording procedures are used in which one part of the total data required for a complete data record is recorded with each diastole of the cardiac cycle.
One of the problems that occur with these MR angiographies is that it is necessary to predict the position of the diastolic rest period of the examined patient during the measuring period in order to record the MR images during this period of the diastole. The heart rate can change during the examination period so that through the changing heart rate the position of the diastole also changes. If a constant heart rate is assumed and it is assumed that the diastole occurs at a fixed point in time, it can occur that, through the change of the rest period during image recording, the rest point of the diastole has not yet occurred or is already over. This has a negative effect of the image quality.
From DE 28 13 830 A1, a device is known that makes heart images by means of cathode beam scanning which determines the position of the diastole for diagnostic imaging.
From Lee S. H. et al. “Analysis of the Heart Rate and its Variation Affecting Image Quality and Optimized Reconstruction Window in Retrospective ECG-Gated Coronary Angiography Using Multidetector Row CT” in IEEE Transactions on Nuclear Science, Vo. 51, No. 1, February 2004, pp. 225-230 it is known how the heart rate of patients changes during computer tomography imaging of the heart.
From US 2003/0174804 A1 a procedure for diagnostic imaging of the heart by means of computer tomography is known in which, by means of the ECG and by means of the mechanical movement of the cardiac region, the period in which to measure the heart is determined.
In “Prediction of Heart Rate Variation during Coronary MRA Using a Neuronal Network,” in Proc. ISMRM 11 (2004), p. 1885, M. Buehrer et al. tried to determine the heart rate by means of neuronal networks in order to improve the imaging quality of the magnetic resonance angiography of the coronary arteries. However, the use of a neuronal network, however, is quite complex.